SCANNING ELECTRON MICROSCOPY
Scanning Electron Microscopy is a microscopy method of looking at samples at very high magnifications using an electron beam. The beam scans the surface of the specimen, and in so doing causes electrons to be released from the sample. These electrons are collected and used to create an image. Magnifications of up to 100 000X can be achieved.
Imaging can be done in both secondary electron and backscattered electron mode. Backscattered electron mode allows contrast in the image on the basis of composition. Heavy elements like niobium will appear bright while light elements like silicon will appear dark. This is a very useful method for phase analysis in metallic materials.
Secondary electron mode creates topographic contrast. This is useful for analysing fracture surfaces to see if the failure was brittle or ductile, or as a result of fatigue if normal light microscopy methods cannot diagnose this.